1. Field of the Invention
When an evaporative cooling unit is provided, air is pumped through water absorptive filters to which water from a suitable source, such as a reservoir, is pumped at a slow rate in order to maintain the filters moist. Of course, when there is no demand for the cooling unit to operate, the system remains in a ready condition without water being pumped to the filters. However, whenever a demand for cooling causes the evaporative cooler to be actuated, a small flow of water to the filters is provided in order that the latter may be moistened. A major problem with an evaporative cooling unit is that as it is used a solid substance, usually calcium carbonate, builds up on the filters or pads as a result of water being evaporated from the filters or pads. The build up of calcium carbonate on the filters or pads greatly reduces the wetted surface area of the pads over which air may be flowed and the efficiency of the cooling unit is reduced appreciably.
In order to prevent the build up of calcium carbonate on the filters or pads of an evaporative cooling unit, a liquid chemical is added into the supply of water for the filters or pads and the chemical added to the water controls the pH of the water and thereby substantially prevents the build up calcium carbonate on the filters or pads.
2. Description of Related Art
Various different forms of apparatus for intermittently dispensing measured quantities of fluids heretofore have been provided such as those disclosed In U.S. Pat. Nos. 1,979,605, 2,505,798, 2,529,937, 2,876,787, 2,960,999, 3,220,435, 3,521,671 and 3,720,230, Canadian Pat. No. 573,875 and British Pat. No. 845,345. However, these previously known forms of apparatus are not capable of performing the intended function of the instant invention in the improved manner accomplished thereby.